Use cases
Anything people argue about can be a market. Here are five kinds.
People
Fans buy COOL, critics buy SUCKS, and every post moves the price. The person can claim the market and earn from every trade.
Sport
Messi or Ronaldo? The debate never ends, so the market never closes. You name both sides.
Politics
A live approval rating. Polls come out once a month, and this price moves with every trade.
Memes
A meme born with its opposite. Haters buy SUCKS instead of launching a vamp, and the creator earns from both sides.
Questions
Any question with no end date. Nobody has to judge it: the price is what the crowd thinks right now.
If people argue about it, it can be a market.